Apparatus for shaving printing plates



3 Sheets-Sheet 1 rll llll IIII fj l If 1.. E. MUELLER APPARATUS FOR SHAVING PRINTING PLATES July 29, 1958 Filed July 1. 1954 uvmvmx. LOUIS MUELLER wrroanav nited States Patent 2,845,009 APPARATUS FOR SHAVING PRINTING ,PLATES Louis E. Mueller, Detroit, Mich., assignor to The Rapid Electrotype Company, Cincinnati, Ohio, a corporation of Ohio Application July 1, 1954, Serial No. 440,639

8 Claims. (Cl. 90-25) The present invention relates to apparatus for shaving printing plates.

It is an object of the present invention to provide an apparatus for shaving printing plates, preferably formed of plastic material, to an extremely accurately controlled and uniform thickness. I

More specifically, it is an object of the present invention to provide apparatus for shaving a printing plate including novel means for supporting the printing plate for advance beneath a shaving blade in such a way as to insure accuracy in thickness of the shaved plate and to prevent the formation of buckle tunnels therein.

More specifically, it is an object of the present invention to provide apparatus comprising a frame, a carriage slidable on the frame, a flat plate supporting bed on the carriage, a head on the frame extending transversely across the path of movement of the carriage, a shaving blade on the head, a plate engaging platen movable toward and away from the bed while the carriage is in loading position, and a flat bottomed shoe located intermediate the platen and shaving blade to press the material of a printing plate downwardly against a gauging surface substantially to the Zone of engagement between the blade and the printing plate.

It is a further object of the present invention to provide apparatus of the character described comprising novel means for leveling the plates and adjusting the spacing between the plates and the bed of the carriage;

It is a further object of the present invention to provide an automatic control system for the apparatus comprising means responsive to movement of the platen into plate engaging position to prevent initiation of movement of the carriage in its cutting stroke until the platen has reached plate engaging position and to prevent such movement after a plate of excessive thickness is provided on the bed.

It is a further object of the present invention to provide power means for advancing and retracting the carriage on the frame, and power means for raising and lowering the platen, together with means effective to prevent initiation of movement of the carriage until the platen reaches a predetermined operation position, and means responsive to completion of the forward cutting stroke of the carriage to actuate the power means to raise said platen upon initiation of the return stroke of the carriage, and means responsive to completion of the return stroke of the carriage for terminating movement thereof.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a plan view of plate shaving apparatus constructed in accordance with the present invention.

Figure 2 is a side elevation of the plate shaving apparatus, with parts broken away.

Figure 3 is an end elevation of the plate shaving apparatus from the loading end thereof.

Figure 4 is an enlarged end elevation of the apparatus with parts sectioned through the cross head.

Figure 5 is a fragmentary plan view of the cutter head with parts broken away.

Figure 6 is a fragmentary sectional view on the line 66, Figure 4.

Figure 7 is a fragmentary enlarged sectional view on the line 77,- Figure 1. Figure 8 is a fragmentary enlarged sectional view on the line 8--8, Figure 1.

Referring now to the drawings, the plate shaving apparatus comprises a frame 10 having Ways 12 formed inits upper surface and receiving a longitudinally slidable carriage 14 having a perfectly fiat horizontal bed 16 providing a surface for supporting a printing plate. In Figure 2 the carriage 14 is shown in the position which it.

occupies upon completion of a forward cutting stroke. At its rear edge the carriage 14 is provided with a pusher bar 18 (Figure 2) having a forwardly and upwardly inclined lip 20 for engagement with the trailing edge of a printing plate as it is advanced beneath the shaving ap-.

paratus.

Means are provided for effecting forward movement of the carriage 14 from its loading position, which is at theleft as seen in Figures 1 and 2, in a cutting stroke so as to advance a printing plate carried thereby beneath a shaving blade and to return the carriage to its initial or loading position. This means comprises an electric motor 22 carried by the frame and connected through a speed. reducer 24 to a driving sprocket at 26. A brake 30 is provided effective to bring the carriage to a quick stop when certain safety controls later to be described are actuated. .Mounted on a ledge 32 provided on the frame is a plate 34 having a sprocket support 36 thereon for carrying a second sprocket. The two sprockets referred to are interconnected by an endless chain 38. A bracket 40 is secured to the frame and extending through an opening in the bracket is an adjusting rod 42 which is connected at the right hand endas seen in Figure 2, to,

the plate 34. Adjusting nuts 44 provide means for adjusting the plate 34 and thereby the tension of the chain 38. Connected to one link of the chain is a square block:

46 which as best seen in Figure l, is movable transversely of the frame in a slot 48 provided at the forward end of the carriage 14. From the foregoing it will be apparent that'as the motor 22 is driven in rotation, the block 46 will travel in a closed path consisting of spaced.

parallel branches interconnected by arcuate portions at the end so that if the motor continued to rotate, the carriage would reciprocate back and forth.

Intermediate the ends of the frame 10 there are provided a pair of upstanding cylindrical head supporting posts 50 which as illustrated in Figure 4 are rigidly connected to the frame 10 by bolts 52. At their upper ends the posts 50 are reduced and threaded as indicated at 53.

Extending upwardly from the reduced threaded portion 53 is .a rod 54 having a pointer 55 thereon cooperating with a scale 56 secured to a cross head cover 57. Thread- Thelower ends of the plungers rest upon the flanges of the posts 50 and urge the cross head 60 upwardly counterbalancing a portion of its weight to facilitate adjustment.

The bevel gears 58 include web portions 74 resting upon.

bushings 76 received in openings 78 in the pads' 59.

Identical constructions are provided at both ends of the cross head and the cross head includes brackets mounting a cross shaft 82 carrying a pair of bevel gears 84 meshing with the bevel gears 58. The shaft 82 at its outer end is provided with an adjusting hand wheel 86. As is apparent, rotation of the hand wheel 86 will results in simultaneous and equal rotation of both of the bevel gears 58, thereby moving these gears upwardly or downwardly on the threaded and reduced portions 53 of the posts 50 and thus raising and lowering cross head 60. The bosses 66 of the cross head include cylindrical guide portions 88 slidable on the posts 50 which guide the cross head in vertical movement.

In order to lock the cross head firmly in adjusted position, the cross head at opposite ends thereof includes recesses 90 which receive wedge blocks 92, as best seen in Figure 5. The wedge blocks 92 are interconnected by a cross rod 94 having a threaded portion engaging a fastening nut 96 at one end. The cross rod 94 at its opposite end has keyed or otherwise secured thereto a locking handle 98. Rotation of the handle 98 in the proper direction tends to draw the blocks 92 toward each other. Each of the blocks has an inclined wedging surface 100 engageable with a side of a supporting post 50, as clearly illustrated in Figure 5.

Movably mounted on the vertically adjustable cross head 60 is a shaving blade 102 which includes means indicated generally at 104 for adjusting the height of the blade and for leveling the blade. Also carried by the cross head 60 is a shoe 106. For this purpose the cross head 60 is provided with a pair of depending bosses 108 which are recessed upwardly as indicated at 110 and have a reduced opening 112 extending into the interior of the cross head. Slidably received within the recesses 110 are vertically movable slides 114 having extending upwardly therefrom pins 116 which are provided with heads 118 located above the reduced openings 112. Disposed between the end surfaces of the recesses 110 and the slides 114 are compression springs 120 urging the slides 114 downwardly. The shoe 106 is provided with transversely extending slots 122 adjacent its end and the slides 114 are provided with flanged end portions 124 slidably received in slots 122. Accordingly, the transversely extending shoe 106 may be removed from the vertical slides 114. The shoe 106 as a unit is vertically movable from its lowermost position which depends upon the adjustment of the headed bolts 116 upwardly. Intermediate its ends the shoe 106 is provided with an upwardly extending member 126 including a headed screw 128 which extends through an opening 130 provided in the bottom of the cross head 60. Mounted on the cross head 60 is a lever 132 which is pivoted as indicated at 134 to a bracket 136 extending upwardly from the bottom surface of the cross head 60. A compression spring 138 bears at its lower end against the upper surface of the bottom wall of the cross head 60 and its upper end is received within a pocket 140 provided on an arm 142 of the lever 132. The lever 132 includes another arm 144 resting upon the upper end of the headed bolt 128 so that upward movement of the shoe 106, as may occur when a printing plate of excessive thickness is advanced beneath the shoe, results in rocking movement of the lever 132 in a counterclockwise direction as seen in Figure 4. The lever 132 includes a third upwardly extending arm 146 having at its upper end an adjustable bolt 148 retained in adjusted position by a lock nut 150. Carried within the hollow cross head 60 is a limit switch LS1 having a plunger engageable by the head of the bolt 148. The function of this limit switch will be described subsequently.

Also carried by the cross head at the side of the blade 102 opposite from the shoe 106 is a shaft 152 carrying thereon a plurality of rollers 154 which operate to encarriage.

4 gage the shaved surface of the printing plate after it has traversed the shaving blade.

The present apparatus is designed particularly for the purpose of shaving printing plates formed of plastic material and it is essential to produce the high degree of accuracy required in these plates that the printing plate be adequately supported during its traverse beneath the shaving blade. One of the problems encountered in attempting to advance printing plates of this type in shaving operations has been the tendency of the printing plate to buckle and thereby to form therein buckle tunnels which destroy the utility of the shaved printing plate and lead to lack of uniformity in the printing operation. In accordance with the present invention a smooth surface platen is provided, the under surface of which is adapted to be brought into engagement with the upper surface of the printing plate and to support it during ad vance toward the shaving blade. Intermediate the edge of the platen 160 and the shaving blade, the upper surface of the printing plate is engaged by the spring pressed shoe 106 and this shoe, as best illustrated in Figure 6, is positioned in close proximity to the cutting edge of the shaving blade 102. Actually, the spacing between the flat under surface of the shoe and the cutting edge of the blade is only sufiicient to provide the requisite clearance for chips and shavings. Thus, both the platen 160 and the shoe 106 combine to press the entire printing plate down in flat condition against the flat surface of the bed 16 of the carriage 14.

It is accordingly necessary to position the platen 160 in a very accurately predetermined position, in substantially absolute parallelism and at a perfectly definitely spacing from the upper surface of the bed 16 of the The means for accomplishing this comprises a housing plate 162 having an upwardly extending flange 164 which in turn is provided with an outwardly and downwardly turned flange 166', the lower end of which is loosely received within a rabbet 168 formed at the upper corner of the platen 160. The upwardly extending flange 164 cooperates with a cover plate 170 to provide a housing designated generally by the reference numeral 172, in which is secured mechanism for leveling the platen 160 and for effecting adjustment thereof towardand away from the bed of the carriage. The housing 172, as best illustrated in Figure 3, is pivoted to brackets 174 as indicated at 176, the housing being connected to an actuating arm 178 which in turn is connected to a piston rod 180 of a piston received in a power cylinder 182 pivoted as indicated at 184 to a bracket 186 secured to the frame 10.

Referring now to Figures 1, 7 and 8, the platen 160 has rigidly secured thereto a plurality of upwardly extending pins 190, these pins having at their upper ends heads 192. The intermediate portion of the pins is of cylindrical form and extends through openings 194 provided in the housing plate 162, as seen in Figure 7. Intermediate the upper surface of the housing plate 162 and the pin heads 192 are compression springs 196 of suflicient strength to provide a force overcoming the weight of the platen and urging the platen upwardly to a position accurately determined by adjustable mechanism later to be described.

Rigidly secured to the upper surface of the platen 160 are a plurality of threaded members 200 having at their lower ends laterally extending flanges 202 secured to the upper surface of the platen 160 as by screws 204. The housing plate 162 has a like number of upwardly extending bosses 206 having cylindrical openings 208 therethrough which receive internally threaded members 210. The members 210 at their lower ends include flanges 212 engaging the lower surface of the housing plate 162. The flanges 212 serve to limit upward movement of the platen 160 and thereby to predetermine the exact position of the platen relative to the housing 172.

Members 210 at their upper ends are reduced as indicated at 214 and have secured thereto sprockets 216. The sprockets 216 are provided with a radially extending split portion as indicated at 218, and have clamping screws or bolts 220 associated therewith so that the sprockets may be rigidly secured to the members 210 or may be released therefrom.

The housing plate 162 has upwardly extending apertured bosses 222 and the cover plate 170 is provided with registering downwardly extending vertically apertured bosses 224. Extending through the apertures of these bosses is -a shaft 226 to which is pinned or otherwise rigidly secured a relatively large driving sprocket 230 having a centralvertically extending boss which together with a bearing 232 is adapted to extend between the lower surface of the boss 224 and the upper surface. of the boss 222. At its upper end the shaft 226 has keyed or otherwise secured thereto a hand Wheel 234, and alsokeyed or otherwise secured to the shaft 226 is an indicating pointer 236'. The upper surface of the cover 170 is provided with a graduated scale 238 which cooperates with the pointer to indicate the exact position of the platen 160 relative to the housing plate 162.

Extending upwardly from the housing plate 162, as best illustrated in Figures 1 and 8, is an apertured boss 240 receiving a pivot pin 242 mounting a plate 244 provided with an arcuate slot 246 concentric with the axis of the pin 242. Extending through the slot 246 is a locking screw 248 which is threaded into a threaded opening in the housing plate 162. -By this means the plate 244 may be angularly adjusted about the axis of the pin 242 and locked in adjusted position. Carried by the plate 244 are a pair of pivot pins 250 on which are mounted idle sprockets 252.

An endless chain 254 is trainedaround the sprockets 216, which are four in number as illustrated inFigure 1, the chain being trained around the large sprocket 230 and also around the idle sprockets 252. Accordingly, angular adjustment of the plate 244 carrying the idle sprockets252 provides means for controlling the tension of the chain 254.

From the foregoing it will be apparent that rotation of the hand Wheel 234 effects equal and simultaneous adjustment of all of the threaded members 200, and hence uniform movement of the platen 160 toward and away from the housing 172. At the same time, the structure provides means for leveling the platen 160. This is accomplished by loosening the sprocket clamping means 220 and thereafter effecting manual adjustment of the internally threaded members 210 to move the corresponding corner of the platen toward or away from the housing plate without aifecting the adjustment of the remaining corners thereof. When the platen has been brought into a level condition or parallelism with respect to the bed 16 of the carriage 14, clamping means 226 may be retightened and thereafter adjustment of the platen 160 may be accomplished by the hand wheel 234 to accommodate printing plates of different thickness.

As best seen in Figure 3, the housing 172 includes laterally extending bosses 260 which carry adjustable abutment screws 262 the lower ends of which are adapted to engage a rigid abutment 264 on' the frame of the apparatus. Carried by the frame is a limit switch LS2 as seen in Figure 2 having a plunger 266 engageable by an intermediate plunger 268 carried by the abutment 264 and extending upwardly thereabove for engagement with the underside of a switch actuating screw 270. The limit switch LS2 is connected into the control system and prevents travel of the carriage 14 from loading position to the position illustrated at the right in Figure 2 until the housing 172 is in predetermined position. This prevents premature movement of the carriage on a cutting stroke and also serves as means to prevent operation of the machine in the event that a printing plate is mounted A third limit switch LS3 (Figure 1) is mounted on the frame and has a plunger 272 adapted to be engaged by a cam 274 extending laterally from one side of the carriage 14. ,A fourth limit switch LS4 is carried by the frame and has a plunger 276 adapted to be engaged by the cam 274 on return of the carriage 14 to loading position. 1

The control circuit includes a stop, reverse, and start switch set indicated at 278. While the details of the particular wiring diagram form no part of the present invention, the control circuit is arranged so that the housing 172 is in elevated position and the carriage14 is at the left as seen in Figure 2. The operation then is to place a printing plate on the bed 16 of the carriage 14 with its trail-, ing edge in engagement .with the follower lip 20. At this time the start button is depressed and power fluid is admitted to the cylinder 182 swinging the housing 172 to the position illustrated in Figure 3. If the plate does not exceed a predetermined maximum thickness, the screw 270 engages limit switch LS2 which starts motor 22. This initiates movement of the carriage 14 to the right and the leading edge of the printing plate advances beneath the shoe 106. If the printing plate is of excessive thickness the shoe is elevated, thus actuating the limit switch LS1 and terminating the cycle. If however, the printing plate is within acceptable thickness limits the leading edge of the printing plate advances beneath the shoe 106 and is maintained in parallelism thereby and pressed against the bed surface 16 of the carriage. Movement of the carriage 14 to the right thereafter results in a shaving operation from the upper surface of the printing plate effected by the ,blade 102. At the completion of the strokethe cam 274 actuates limit switch LS3 which reverses .the direction of application of pressure fluid to the cylinder 182 and raises .the housing 172 together with the .platen 160.. Continued operation of the motor 122 reverses the carriage and reversed travel continues until the cam 274 actuates the limit switch LS4, which breaks the circuit to the motor, thus terminating a cycle.

The drawings and the foregoing-specification constitute a description of the improved apparatus for shaving printing plates in such full, clear, concise and exact terms as to enable any person skilled in the art to pratice the inven tion, the scope of which is indicated by the appended claims.

What I claim as my invention is: 1

1. In a printing plate shaving machine having a translatable table movable beneath a shaving blade, an ad justable platen assembly movable toward and away from said table, said assembly comprising a platen having a plurality of upstanding threaded studs integrally secured thereto, a support plate overlying said platen and having a plurality of openings respectively overlying said studs, internally threaded elements rotatably received in the openings, means connected to said elements effective to prevent movement of said elements axially of said openings, and drive means for turning all of said elements simultaneously.

2. In a printing plate shaving machine having a translatable table movable beneath a shaving blade, an adjustable platen assembly movable toward and away from said table, said assembly comprising a platen having a plurality of upstanding threaded studs integrally secured thereto, a support plate overlying said platen and having a plurality of openings respectively overlying said studs, internally threaded elements rotatably received in the openings, means connected to said elements effective to prevent movement of said elements axially of said openings, and drive means for turning all of said elements simultaneously, said drive means comprising a sprocket connected to each of said elements and a drive chain connected to all of said sprockets.

3. In a printing plate shaving machine having a translatable table movable beneath" a shaving blade, an adjustable platen assembly movable toward and awayfr'om said table, said assembly comprising a platen having a plurality of upstanding threaded studs integrally secured thereto, a support plate overlying said platen and having a plurality of openings respectively overlying said studs, internally threaded elements rotatably received in the openings, means connected to said elements effective to prevent movement of said elements axially of said openings, drive means for turning all of said elements simultaneously, said drive means comprisinga sprocket connectcd to each of said elements and a drive chain connected to all of said sprockets, and means releasably connecting each of said sprockets to one of said elements, whereby each of said sprockets may be disconnected to provide for independent adjustment of a stud and element set without disconnecting said chain.

4. In a printing plate sh'aving machine having a translatahle table movable beneath a shaving. blade, an adjustable platen assembly movable toward and away from said table, said assembly comprising a platen having a plurality of upstanding threaded studs integrally secured thereto, a support plate overlying said platen and having a plurality of openings respectively overlying said studs, internally threaded elements rotatably received in the openings, means connected to said elements efiective to prevent movement of said elements axially of said openings, drive means for turning all of said elements simultaneously, said drive means comprising a sprocket connected to each of said elements and a drive chain connccted to all of said sprockets, means releasably connecting each of said sprockets to oneof said elements, whereby each of said sprockets may be disconnected to provide for independent adjustment of a stud and element set without disconnecting said chain, and resilient means connecting said platen and support plate urging said platen upwardly toward said support plate to facilitate adjustment of said platen relative to said support plate.

5. Plate shaving apparatus comprising a fiat plate supporting table, means for reciprocating said table horizontally in cutting and return strokes, a plate shaving blade, means supporting said blade in position above the path of travel of said table, a platen having a smooth flat surface, means supporting said platen for movement between 21 working position in which it is spaced slightly above the upper surface of the table to slidingly engage and support the upper surface of a printing plate and a loading position in which said platen is spaced substantially away from said table to permit unobstructed loading of a printing plate thereon, a shoe having a smooth flat under-surface located directly in front of the shaving blade and spaced therefrom a distance only sufficient to ermit passage of chips and shavings therethrough, said shoe being located directly adjacent the edge of the platen adjacent the shaving blade when'the platen is in working position. means movable with said table and engageable with the rear edge of a printing plate supported on said table to feed the printing plate forwardly on the table in sliding relation With the under-surfaces of said platen and shoe and beneath said blade, said platen and shoe together providing means effective to prevent any tendency of the printing plate to buckle and thereby to prevent the formation of buckle tunnels.

6. In apparatus for shaving a printing plate to an accurately controlled uniform thickness including an elongated frame and a transversely extending shaving blade intermediate the ends thereof, the improvement which comprises a plate supporting carriage movable beneath the blade having an accurately formed flat plate supporting surface, a platen carried by said frame and having an accurately formed fiat undersurface engageable in sliding relation with the upper surface of a plate on said carriage, means for moving said carriage to advance a plate thereon beneath the blade, an elongated pressure shoe having an accurately formed flat lower plate engaging surface, said shoe being located between said platen and blade in position to engage the upper surface of a plate just prior to engagement'thereof with the blade.

7. Structure as defined in claim 6 in which said shoe is spaced from the blade a distance sufficient only to provide chip clearance.

8. In apparatus for shaving a printing plate to an ac curately controlled uniform thickness including an elongated frame and a transversely extending shaving blade intermediate the ends thereof, the improvement which comprises a plate supporting carriage movable beneath the blade having an accurately formed fiat plate supporting surface, a rectangular platen carried by said frame and having an accurately formed flat undersurface engageable in sliding relation with the upper surface of a plate on said carriage, means for movingsaid carriage to advance a plate thereon beneath the blade, a platen support hinged to said frame, means for effecting accurate adjustment of said platen relative to said support comprising independently adjusted threaded elements interconnecting the corners of said platen and said support, and means for effecting simultaneous and equal adjustment of all of said elements.

References Cited in the file of this patent UNITED STATES PATENTS 1,054,130 McKee Feb. 25, 1913 1,297,108 Cunningham Mar. 11, 1919 2,040,437 Huck May 12, 1936 2,083,419 Andrews June 8, 1937 2,651,240 Sutton Sept. 8, 1953 2,688,275 Hammond et a1. Sept. 7, 1954 

